The present invention relates to packages for food products, especially meat products, and particularly to packages having a tray and lidstock, in which the lidstock of the package comprises a shrink film, especially a barrier shrink film.
It is common practice in packaging many goods, including food items, to use a thermoformed tray. The tray provides a cavity into which a food or other product can be placed. In some applications, instead of thermoforming a web, a preformed tray is used. This can be made from a variety of materials; typical is foamed polystyrene.
A non-forming web (lidstock), typically a laminate, is fed from a roll across the tray, and covers the product. Sometimes, the non-forming web is sealed to the tray edges to form the finished package. Sometimes the lidstock includes an oxygen barrier layer to provide longer shelf life to the packaged product.
To complement the oxygen barrier feature of some lidstocks, and provide a means to adhere the lidstock to the tray, some trays have a film or layer of oxygen barrier material adhered to the interior cavity of the tray. This is done in such a way that the lidstock can be sealed to the oxygen barrier film of the tray. This barrier layer is sometimes supplied by adhering a flexible oxygen barrier film or layer to an e.g. polystyrene foam sheet prior to thermoforming into trays. Alternatively, the oxygen barrier film is adhered to the tray after the tray has been made. U.S. Pat. Nos. 4,847,148 and 4,935,089 (Schirmer) disclose examples of this.
Commercially sold lidstocks suffer from several shortcomings. They tend to have relatively poor optical properties. This means that the aesthetic appearance of the overall package is diminished.
Also, these materials are relatively thick, and therefore raise waste disposal problems.
Where modified atmosphere is used in the interior of the package, the food article oftens absorbs some of the gas, resulting in a loose lidstock.
The inventor has discovered that a trayed package can be made with a shrinkable lidstock, preferably including an oxygen barrier layer. This lidstock provides improved clarity and tightness in the finished package, and a downgauged lidstock which uses less material.
The present invention provides a package for meat and other products wherein the aesthetic properties of the package are substantially improved, while the thickness of the lidstock is reduced. This result is accomplished while substantially maintaining the overall performance and function of the package in terms of protection of the packaged product.
In one aspect, the present invention relates to a package comprising a product support member having a cavity formed therein; a product disposed in the cavity; and an oriented, heat shrinkable lidstock film disposed over the product, and sealed to the product support member.
In another aspect, the present invention pertains to a method of packaging a product comprising providing a product support member having a cavity formed therein, and a flange around the perimeter of the member; placing the product in the cavity formed by the product support member; placing an oriented, heat shrinkable film over the product; sealing the oriented, heat shrinkable film to the flange of the product support member; and cutting at least some of the oriented, heat shrinkable film extending beyond the perimeter of the product support member.
In a preferred embodiment, a package comprises a foamed polymeric tray having a first surface, said surface defining a cavity formed therein for receiving a food product, and a flange disposed around the periphery of the tray; a thermoplastic film liner adhered to the first surface and the flange of the tray, the film liner comprising an oxygen barrier material; a food product disposed in the cavity; and an oriented, heat shrinkable film disposed over the product, and sealed to the thermoplastic film liner in the region of the flange of the foamed tray, the oriented, heat shrinkable film forming a bead along the flange, the film comprising outer layers comprising an olefinic polymer, and an intermediate layer comprising an oxygen barrier material. The oriented, heat shrinkable film most preferably does not extend beyond the flange of the foamed tray.
The present invention is advantageous in that it offers a package with a thinner lidstock with better optics than conventional laminates. It also provides a package with a neatly trimmed lidstock around the perimeter of the package, along the tray flange, by eliminating excess film overhang. The invention provides a lidstock that offers good package tightness during storage.